The transmission of high bandwidth signals between widely separated locations is commonly done via special connections to high bandwidth transmission lines which are interconnected to form a direct point-to-point connection from the source to the receiver of video or other high bandwidth signals. One well-known example is the cable television industry, in which a video signal is broadcast via wideband transmission lines to several receivers. Other examples of point-to-point wideband connections are state of the art video teleconferencing facilities and wideband connections between computers. Such direct connections are expensive and great economical advantage can be gained by switched interconnections, allowing any of a number of sources to be connected to any of a number of destinations, as is commonly done in a local exchange for the transmission of narrowband voice signals. One reason that this has not been done for video signals is the lack of wideband facilities which can be readily switched. One prior art approach to this problem is to create a wideband switching facility from a number of narrowband channels. Such an arrangement is taught in the U.S. Pat. No. 4,704,716 entitled "Method and Apparatus for Establishing a Wideband Communication Facility Through a Communication Network Having Narrow Bandwidth Channels". In that arrangement, the wideband facility is comprised of a number of segments, each including a plurality of narrowband time division multiplex channels. Wideband signal data received in a given time frame from one segment is assembled into a single time frame for transmission to another segment. In this manner, a switching system having only narrowband channels is employed to switch wideband signals by disassembling wideband signals, switching them and reassemblying them. A disadvantage of this arrangement is the cost in terms of equipment and real-time in the disassembly and reassembly operations.
Prior art reconfigurable broadband interconnection devices are known. These are standalone systems for interconnecting high bandwidth transmission facilities such as the commonly known DS1 (1.544 Mbps) and DS3 (44.736 Mbps) transmission links. Some crossconnect systems include a digital controller responsive to control messages from the craft personnel or operations systems to reconfigure interconnections between incoming and outgoing high bandwidth transmission links. Once an interconnection has been established in a crossconnect system, however, the transmission links remain connected in the same configuration until an external event occurs such as a link failure or changing traffic conditions, which requires reconfiguration of routes. A disadvantage of this prior art arrangement is that there is no provision for establishing switched connection in real-time on a connection demand basis.
Another prior art arrangement is disclosed in U.S. Pat. No. 4,763,317 entitled "Digital Communication Network Architecture for Providing Universal Information Services". The patent discloses a switched integrated wideband and narrowband multiservices digital network comprising a central switching node with wideband and narrowband switching fabric. The switching fabrics are connected through shared line interface units to wideband optical fiber communication links. Narrowband channels are switched between optical links by means of the narrowband fabric and wideband channels are switched between the optical links by means of the wideband fabric. A disadvantage of this arrangement, is the cost of such an integrated structure, including the cost of special purpose interface circuits. A need exists in the industry for a relatively inexpensive and flexible arrangement for providing services using high bandwidth, such as video conferencing among subscribers, pay-per-view television services, and the like.